2 Answers
2

You should remove some of the older kernels. Typically people only keep the last 2 or 3 kernels and delete any older ones. You can remove the older kernels by following the steps in this question: How do I free up more space in /boot?

Whether it is a lot or not totally depends on the size of your boot partition. Each kernel takes about 25Mb of space in /boot, and you have 8 of them, so if your /boot is around 200Mb then everything can be explained easily.